Production of carbon monoxide and other gases from carbonaceous materials



GAUCHER PRODUCTION OF CARBON MONOXIDE AND OTHER G 2558,76 ASES July 3,195 L. P.

FROM CARBONACEOUS MATERIALS 2 Sheets-Sheet l Filed Feb. 10, 1948INVENTOR, PY G July 3, 1951 l. P. GAUCHER PRODUCTION OF CARBON MONOXIDEAND OTHER GASES FROM CARBONACEOUS MATERIALS 2 sheets-Sheet 2 Filed Feb.10, 1948 SLAG NVENTOR.

/ .ATToR/vsys Patented July' 3, 1951 im i OTHER GASES 'FRQM MATERIALSGARBONACEOUS Leon P. Gaucher, Mount Vernon, N. Y., assignor to The TexasCompany, New York,N. Y., a corporation of Delaware Application February10, 1948, Serial No. 7,446

This invention relates to a process and apparatus for the generation ofgases comprising carbon monoxide from carbonaceous materials. In one ofits more specific aspects it relates to the improved apparatus andimproved method 5 Claims. (Cl. 48-206) of injecting reactants anddiluents into the reactor. l

In the gasiiication of carbonaceous material with oxygen, particularlysolid fuels, the reaction a process and apparatus for the generation of52' between the oxygen and fuel results in the proa mixture of carbonmonoxide `and hydrogen, duction of carbon dioxide according to thesuitable as a feed for the synthesis of hydroequation:

carbons, from powdered coal.

The synthesis of hydrocarbons by the inter- @FOR-CO2 action of carbonmonoxide and hydrogen is well l0 The' Oxidation reaction being highlyexothel'mw' known. A number of processes are known to be releases largequantities 0f heatefieoiive for hydrocarbon synthesis. in general Thecarbon dioxide. so produced. in cvntat liquid hydrocarbons are mosteffectively pro- With hOt carbon. in turn, reaals With the Cal'bn ducedby the interaction of carbon monoxide and l DlOdilCe calbOIl mODOXldeIhydrogen at an elevated temperature and pres- C02+C=2C02 sure in thepresence of a suitable catalyst, usually an element of the iron group ofthe periodic Steam also lfeats with heated carbon t0 produce table ofthe e1ementscarbon monoxide and hydrogen:

The present invention is concerned with the f H+C=C0+H2 generation of amixture of carbon monoxide and 20 hydrogen. The invention isparticularly suited These reactmns an? endothermlc rqum? heat to theproduction of a feed gas for the synthesis from another Source' Theequmbrmm ls f dependent upon the temperature. Heat of hydrocarbons.Liquid or sohd carbonaceous our d thd t. t. fuels may be used, e. g. ahydrocarbon fuel oil, bor e .mdof emlr or lf gc lo rea? lons any coal,etc.; the method and apparatus is especially .e supp-he rom e 0x1 a lonreactmn' T us useful when powdered coal is used as thel feed m a' gasgenerator there Shu1d.be a free trans' materiaL fer of h eat between thezone in which carbon An object of this invention is to provide a gggefgeei ndrtegvzone .hwmcl imho process for the generation of carbonmonoxide Theew ter c huir f ti1n w1 car n' and hydrogen fromcarbonaceous materials. a' gas S eac on' Another object is to provide aprocess par- CO-i-HzOm-I-Ha ticularly suited to the generation of a feedgas for the synthesis of hydrocarbons from coal. EL? :'Illsigttacrlatshgeggo' The wagt Still another object is to provide an improved enceon e method for size reduction of coal and the like thermal balance--mthe generator' At about A f th b t f th t to ,d' 35 1500 F., theequilibrium constant for the water ur er 0 lee 0 5,mven on 1S prov e gasshift reaction is unity. At higher temperapparatus for the generation ofcarbon monoxide atures the reaction tends to favor production andhydrogen from carbonaceous materials. of carbon monoxide and Water.consuming hy Gasication of powdered coal by partial com drogenanda1-bon dioxida is undesirable bustion in cylindrical generators has beenpro- 40 since hydrogen, which is desirable in the prod posed heretofore.To the best of my knowledge, uct gas, is consumed. The reactions betweenhowever, these have not been commercially SUC carbon and carbon dioxideor water are much cessful. Horizontal reactors of this sort were slowerthan the reaction of carbon with free tried in Germany but were notdeveloped beoxygen, The reactions of carbon with carbon Vond theexperimental Stage. Marly Problems dioxide under generator conditionsare over twice remained unsolved when the work was abanas fast as thosewith Nateldoned. Dculties particularly were experienced There are'therefore, several conditions to be in Obtaining Substantially COllPleteIGaCOIl 0f met in the generator. The heat released by the Carbon and inPreventing undesirable Slag acexothermic reactions may be utilized tosupply cumulation due to fusion of the ash. 'I'he method 50 the heat forthe endothermic reaction Heat and apparatus of my invention improves thetransfer from the exothermic zone to the endorate of carbon reaction,resulting in substantially thermic zone of the generator should be verycomplete carbon cleanup. Handling of slag rapid and unobstructed.accomplished without particular difliculty due to For eicientutilization of carbon, the particle size of solid fuels must be verysmall, particularly all temperature of the reactor. It is important thatincompletely reacted solid particles be kept from contact with thecooler walls of the reactor or from the molten slag in which it may betrapped.

The second phase:reactions are Aincreased ifl 4 containing gas fed tothe generator.. When contacted with concentrated oxygen, preferablypreheated, the dry exterior surface of the coal particley reactsviolently with oxygen, rapidly releasing heat which in turn heats theinterior of the particle so rapidly that the particle is disintegratedor exploded because of the'expansion of steam generated in the pores.This further the `concentration of carbon dioxide producedA greater withalsolid fuel than with a gaseous or liquid fuel. Thus,'if it is possibleto burn natural gas completely with a ratio of free oxygen to carbon of0.52, the ratio must be 0.60 or higher to burn coal completelyunder flowconditions. Why this should be so is not certain. It may be, however,thatV because the reactions do take place in two stages and because thereaction of unburned carbon in coal or solid fuel with carbon dioxide ismore rapid than the reaction of the carbon with water, it is necessaryfor subsequent efllcient performance to attain a high concentration ofcarbonl dioxide in the exothermic zone. The only way in which this canbe done in the generator is by the use of concentrated free oxygen forthe exothermic reaction.

The present invention will be described, for the sake of simplicity,with reference to coal as a fuel. It will be understood that coal isused as a specific example and that the apparatus and method describedis Anot necessarily limited to the use of coal. In accordance with thisinvention'coal is ground or otherwise pulverized to as small a size asgiven equipment will economically 1 permit.. It is then surface dried sothat there is no tendency for thevpowlder to agglomerate. but moistureremains in the pore space within the coal particle itself. The powderedcoal may be surface dried by passing it rapidlyover a heated surface sothat the exterior surface of the particle is heated to the dryingtemperature but the interior does not reach a temperature suiiicient todrive moisture from the pore spaces. Another method of surface dryingthe powdered coal is by suspension of the powder inca stream of heatedinert gas. for example, iiue vgas at a temperature` suilicientlyelevated to rapidly rcmove surface moisture. After a short contact timethe coal particles are separated from the-j heated gas, for example, asby means of a cyclone separator,and fed to the generator before anyappreciable quantity of moisture is evapby volume 0rreduces the size ofthe particles. The resulting powdered coal then reacts with additionaloxygen to heat the particle individually through and through to thereaction temperature.

'I'he gasification may be carried out at atmospheric or superatmosphericpressure; in the process of my invention the gasification is preferablycarried out at elevated pressure. A pressure in excess of pounds persquare inch gauge in the generator is preferred.

A number of advantages may be expected from operation atsuperatmospheric pressure. The product gases so obtained are at apressure suitable for further use saving compression costs in Vhandlingthe product, the volume of which is in excess of the volume of thecharge gases. The use of elevated pressure results in higher absoluteoxygen partial pressure in the generator in contrast to low pressureoperations and thus rev action rates are increased.y Other advantages ofpressure gasification are reduction of the size of the requiredequipment and improved heat transfer over shorter distances.

Eiiicient heat transfer from the exothermc to the endothermic reactionsis very important to efficient operation. A portion of the heat transferis by direct radiation; the balance, by convection. Transfer of heatlfrom the exothermic to the endothermic zonesby both radiation andconvection is very efcient in the method and apparatus of thisinvention.

The heated powdered coalvand resulting gases produced by oxidation,Acomprising ycarbon dioxide, Dass directly to an endothermic zone. Steamis supplied to the endothermic zone in a preheated condition,for'example at 10001500 F; The steam so introduced results in improvedreaction of the carbon dioxide with carbon. It is believed that steamalso promotes or catalyzes the reaction: I

This results in rapid replacement of CO2 reacted with carbon so long asfree oxygenV is available. Such a promoteris highly desirable because ofthe low oxygen concentration in the endothermic zone` 'I'he steam andoxygen streams are preferably VAinjected into the generator in such amanner that the particles of powdered coal assume a long rotary'paththrough the reaction zone with a low incidence of collision with thewalls of the reactor.

The apparatus described herein and forming a part of -my inventionprovides for carrying out the reaction in a most efficient manner aswill be more fully brought out yin the following detailed description.'y

Fig. 1 is an elevational view of a preferred embodiment of l'apparatussuitable for carrying out the process of my invention.

Fig. 2 is a vertical cross-sectional 'view of the apparatus illustratedin Fig. 1'.

Fig. 3 is a horizontal cross-sectional view taken along the plane 3 3 ofFig. l. y

Fig. 4 is a vertical cross-sectional viewv of another embodiment ofapparatus suitable for carrying out the. process and forming a part ofthe present invention.

Fig. 5 is a horizontal cross-sectional view taken along the plane 5-5 ofFig. 4.

These generators illustrated in the drawings are particularly suited forthe gasication of powdered coal and other carbonaceous materialscontaining volatile matter.` For the purpose of facilitating thedetailed description of the apparatus illustrated, the description willbe made throughout with reference to powdered coal as the solidcarbonaceous material. To distinguish the generator of Figs. l to 3 fromthe generator of Figs. 4 and 5, the former will be referred to as adownow generator and the latter as up upilow generator.

With reference to Figs. 1 to 3, the generator is provided with an outercylindrical steel shell 6 capable of withstanding operating pressure anda refractory lining 'l of a material suited to the temperatureconditions encountered in operation. Powdered coal is introduced intothe generator through a pipe 9 which enters the upper end of thegenerator, or the exothermic zone, adjacent the inner wall andtangential thereto. Preferably, the upper end of the generator or theprimary oxidizing zone I0 is frustreconical in cross section as isillustrated in the gures. Oxygen is supplied to the zone through anoxygen line II and oxygen header I2. From the oxygen header a series offeed pipes "I3 introduce the oxygen as controlledby valves Il into theexothermic zone immediately below the point of introduction of the' coaland tangential to the inner surface of the generator. The oxygen feedpipes I3 terminate in a series of ports I6 at the inner wall of theoxidation zone.

Steam is-introduced into the generator in accordance with the process ofthis invention immediately below the exothermic zone. The steam entersthe reactor through a series of ports I8 which are so spaced andarranged along the wall of the generator'that the particles of coal aredirected upwardly and away from the walls. The arrangement of ports willbe discussed in greater detail hereinafter. The steam is supplied to theports I8 through a series of feeder pipes I9 in amounts controlled byvalves 2l. 'I'he feeder pipes I9, in turn, are supplied from headers 22with steam which enters the system through the steam line 23 and is fedinto the headers by the distributing ring 2l.

Molten ash and slag formed by burning of the coal is collected at thelower end of the generator from which it iiows through the slag tap 26into an insulated slag disposal pipe '21 provided with a refractorylining 28.

` The generated gases comprising' carbon monoxide and hydrogen arewithdrawn through a chimney 29 at the lower end of the generator intothe product gas line 3| which is lined with.

a suitable refractory 32. A shield 33 over the open end of chimney 29prevents slag and ash particles from dropping into the chimney.

The synthesis gas is quenched by a' water spray. Water is suppliedthrough line 34 to a spray head 36 disposed within the outlet passagefrom chimney `29. By this means the hot synthesis gas may be cooled to atemperature below that at which undesirable reactions take place andbelow the melting point of the ash. Any entrained particles of moltenash or slag are converted to small solid particles in the form of a ilyash which can be readily removed from the synthesis gas by means of amechanical separatorI for example, a cyclone type separator.

In the upiiow generator illustrated in Figs. 4 and 5, the generatorcomprises a cylindrical steel vessel 5I capable of withstanding theoperating pressure lined with a. suitable refractory material 52. Thecoal is fedinto the exothermic zone 53 of the generator through pipe 54and nozzle 55. Oxygen enters the exothermic zone through a series ofports 56 which are so spaced and directed relative to the interior ofthe generator :fla-'1 the particles of coal are given a spiral upwardmotion away from the walls of the generator. rangement of the ports isdiscussed in more detail hereinafter. Oxygen is supplied to thegenerator through the oxygen line 51. The oxygen is fed into adistributor ring 58 from which a number of oxygen headers 59 carry it tothe individual feeder pipes 6I which supply the ports 54. The ow may becontrolled in the individual feeder pipes by the control valves 62.

Immediately above the exothermic zone 53 is an elongated endothermiczone 63 wherein unburned particles of carbon leaving the exothermic zoneare reacted with carbon dioxide for the production of carbon monoxide.Steam is introduced in accordance with the process of my invention intothe endothermic zone through a series of ports 66. The steam is suppliedto the system through a steam line 61, distributor ring 68, and steamheaders 69. Steam from headers 69 may be admitted to the endothermiczone of the `generator through feeder pipes 1I which supply the ports 66in desired amounts'as controlled by valves 12. The ports 66 and supplylines 1I are so spaced and directed relativeto the endothermic zone ofthe generator as to impart an upward motion to the particles of carbon.The particles are suspended by the upowing gas stream from theexothermic zone augmented by steam introduced through ports 66. Thearrangement of the ports 66 and supply pipes 1 I will be discussed inmore detail hereinafter.

The ash and slag is melted at the temperatures prevailing in thegenerator and tend to agglomerate and drop out of suspension or run downthe walls. Molten ash and slag accumulating in generator are withdrawnthrough a slag tap 13 at the lower end of the generator from whence' itis conducted away for disposal through a slag line 14 lined'with asuitable refractory material 16.

The generated gases rare withdrawn from the top of the generator by theproduct gas line I8 which is provided with a suitable refractory lining19. Synthesis gas removed through pipe 18 may be quenched in anyconventional manner. Quenching is beneficial to reduce the temperaturebelow the temperature at which undesirable reactions take place at anappreciable rate and below the melting point of the ash. Ash which iscooled below the melting point in the form of ily ash gives littledifculty in handling with the gas stream and may be separated from thegas by any suitable means, for example, by means of a cyclone typeseparator.

In the operation of the generators, oxygen is fed at operating pressureinto the generator in the exothermic section in amounts such that highyields of carbon dioxide are produced. The contact time in the oxidationzone is insuiiicient to completely consume the carbon so that carbon isavailable for reaction with carbon dioxide in the endothermic zone.

Steam introduced into the endothermic zone The arf reactor.

'l retards consumption of .carbon dioxide by the reverse water gas shiftreaction so that the carbon dioxide is available for reaction withcarbon to produce carbon monoxide, as explained here? inabove. The steamis preheated to the desired temperature as is known in the art: Steammay Y be heated to temperatures as high as 3000n F. and Y possibly to4000 F., for example, by passingvthe steam ,into contact with hotsolids.The so-called pebble heater lis suitable for preheating the steam tosuch'temperatures. f

In the interests of clarityand simplicity of illustration, such detailsas insulation of the steam supply lines, support members, and auxiliaryequipment not necessary to the description of the generator have beenomitted. The slag disposal The product gas is substantially free fromcaf bon dioxide and has a ratio of hydrogen to carbon monoxide of 0.65on a molal basis. l. The yield of Vcarbon monoxide and hydrogen isapproximately 2600 pounds or 2485 pounds carbon monoxide and 115 poundshydrogen.

Example II When the generator temperature is increased to 3500 F., thequantity of steam supplied to the reduction zone is 900 pounds for thesame quantity of coal. The product gas 'contains from about 'I to about10 mol per cent carbon dioxide. A yield of approximately 3000 pounds ofcarbon monoxide and hydrogen is obtained with a molal ratio of hydrogenvto carbon monoxide of 0.52.

On a weight basis the yield of carbon monoxide is All of these ports areutilized for the introduction Y of gases into the reaction zone. Theports are arranged and directed to spiral the gases upwardly through thereaction zones and at the same time direct the unreacted particles ofcoal away from the walls of the generators. This is accomplished bydirecting the gas stream up- Y wardly from the horizontal and inwardlyfrom the tangent with the inner wall of the generator. Preferably, theport discharges the gas upwardly at an angle of from about 5 to about 30,from the horizontal and inwardly at an angle of from 5 to about 30 fromthe tangent. The ports are arranged so that the gases do notimpinge-dlrectly against the wall of the vessel but are di,

rected into the gas stream from an adjacent port.

Thus, particles of coal entrained in the gas streamare directed from onestream .to another and.

spiraled upwardly away from the walls of the In the downow generator ofFigs. 1 to 3, the action of the steam admitted through the ports servesto hinder or delay the settling of the particles, particularly along thewalls vand to keep the particles from contact with the walls. In theupflow generator, the action of the oxygen and steam entering the portsand thevelocity of the gas in the generator serves .to entrain theparticles carrying them upwardly through the reaction zones.

Typical results of operations in accordance with the process of myinvention are given. in the followingl examples. It will be evident thatthe examples are merely illustrative of the invention and no unduelimitation is imposed thereby.

Example I Coal having the following proximate analysis is used as feedfor gas generation by the method of this invention.

Wt. per cent Moisture 4.3 Volatile matter 39.7 Fixed carbon 46.7

Ash 9.3

The generator is operated at a temperature of 2000 F. Sufficient oxygen'is supplied to give a ratio of free oxygen to carbon of 0.7. Whilefeeding 1700 pounds of coal, 630 pounds of steam is fed to the reductionzone of the generator.

oxidize only a portion of said powdered fuelv thereby liberating heatand producing a gaseous about 2890 pounds and the yield of hydrogen is107 pounds;

Obviously many modifications and variations of the invention as aboveset forth may be made without departing from the spirit and scopethereof and only such limitations should be imposed as are indicated inthe appended claims.

Iclaim:

1. In a process for the generation of. carbon monoxideV and hydrogenfrom a solid carbonaceous fuel by reaction with oxygen and steam, the

improvement which comprises introducing said solid carbonaceous fuel inpowdered form into the upper end of a vertical elongated cylindricalreaction zone, contacting said powdered fuel in said zone at the upperend adjacent the fuel inlet with a gasV containing in excess of 90 percent free oxygen by volume in an amount suiiicient to reaction productcontaining carbon dioxide, passing the resulting hot gaseousreactionproduct and heated residual powdered fuel through said reaction zone tothe lower end thereof, and introducing steam into said reaction zone ata plurality of spaced points on the periphery of said zone and i alongthe' path of said fuel at an angle upwardly toward the inlet end from 5to 30 from the horizontal and inwardly from 5 to 30 from the tangent toimpart a rotary motion to the reactants and products, and withdrawing.the resulting product ygases comprising carbon monoxide and hydrogenfrom said lower end of 'said reaction zone.

2. A process as defined in claim 1 wherein the pressure within saidreaction zone is maintained in excess of about 100 pounds per squareinch gauge.

3. The methodas deiined'in claim ,1- wherein said solid carbonaceousfuel is surface dried and Y contains moisture in its pore spaces.

4. A process as defined in claim 1 wherein the plurality of points atwhich the steam is introducedlnto the reaction zone are spirally spacedalong the periphery of said reaction zone and the path of the stream ofsteam into the reaction zone at each of said points is directed into thepath of a stream of steam introduced into the reaction zone at anadjacent point.

5. In a process for the generation of carbon monoxide andhydrogen from asolid carbonaceous fuel by reaction with oxygen and steam, theimprovement which comprises introducing said solid carbonaceous fuel inpowdered forminto the upper end of a vertical elongated cylindricalreaction zone, contacting saidpowdered fuel in said zone at the upperend adjacent the fuel inlet with an oxygen-containing gas in an amount 9sumcient to oxidize only a portion of said powdered fuel therebyliberating heat and producing a gaseous reaction product containingcarbon dioxide. passing the resulting hot gaseous reaction product andheated residual powdered fuel 5 through said reaction zone to the -lowerend thereof, and introducing steam into said reaction zone at aplurality of spaced pointson the peripheryof said zone and along thepath of said fuel tangentially and at an angle upwardly toi0 ward theinlet end to impart a rotary motion to the reactants and products, andwithdrawing the resulting product gases comprising carbon monoxideandhydrogen from said lower end of said reaction zone.

LEON P. GAUCHER.

nEFEaENEs crrl 'Y The following references are of record in the me o!this patent:

UNITED STATES PATENTS Number Name Date 1,039,998 Hirt sept .24,19122,302,156 TotzekV v- Nov. 17,1942

" FOREIGN PATENTS Number Country Date 413,130 Great Britain Aug; 4, 1933OTHER REFERENCES Haslam and Russell: Fuels and Their Com- 5 bustion,"McGraw-Hill Book Company, l 1926,

N. Y., page 484.

5. IN A PROCESS FOR THE GENERATION OF CARBON MONOXIDE AND HYDROGEN FROMA SOLID CARBONACEOUS FUEL BY REACTION WITH OXYGEN AND STEAM, THEIMPROVEMENT WHICH COMPRISES INTRODUCING SAID SOLID CARBONACEOUS FUEL INPOWDERED FORM INTO THE UPPER END OF A VERTICAL ELONGATED FORM INTOREACTION ZONE, CONTACTING SAID POWDERED FUEL IN SAID ZONE AT THE UPPEREND ADJACENT THE FUEL INLET WITH AN OXYGEN-CONTAINING GAS IN AN AMOUNTSUFFICIENT TO OXIDIZE ONLY A PORTION OF SAID POWDERED FUEL THEREBYLIBERATING HEAT AND PRODUCING A GASEOUS REACTION PRODUCT CONTAININGCARBON DIOXIDE, PASSING THE RESULTING HOT GASEOUS REACTION PRODUCT ANDHEATED RESIDUAL POWDERED FUEL THROUGH SAID REACTION ZONE TO THE LOWEREND